Automatic clamping mechanisms are extensively employed in production lines such as transfer lines. In a typical transfer line, various machining operations, such as drilling, boring, milling or gauging, may be performed on a workpiece at sequential work stations to yield a finished part. The workpieces at the various work stations are clamped simultaneously, machined or otherwise worked upon, unclamped, and transferred simultaneously to the next stations in the sequence. The workpiece clamps are initially moved rapidly in rapid approach to a location near the fully clamped or unclamped position, and then are fed more slowly to the final positions. Various devices such as hydraulic actuators are conventionally employed to perform the clamping and unclamping functions. Such actuators are expensive, are subject to failure, and are difficult to control, tending to slam the clamp against the clamp stop in the open position and/or into the workpieces in the clamped position.
It is a general object of the present invention, therefore, to provide a clamping arrangement character which overcomes the aforementioned deficiencies in the art. More specific objects of the invention are to provide such a clamping arrangement which is easy to control and which firmly holds the clamp against the workpieces and/or the clamp stop.